ALBUQUERQUE (AP)— After a nearly 10-year campaign by environmentalists, hunters and tourism officials to gain wilderness protection for the Organ Mountains and Desert Peaks in Southern New Mexico, the White House said Monday that President Barack Obama will declare almost 500,000 acres of mountain ranges above the Chihuahan Desert a national monument this week.

Supporters hailed Obama’s announcement, planned for Wednesday, as crucial for preserving important historical, cultural and nature sites while creating new jobs and generating millions of dollars annually in new revenue from tourism and outdoor recreation.

Opponents, however, fear the designation will interfere with rancher’s grazing rights and impede law enforcement access and authority, making it easier for Mexican drug cartels to open new smuggling routes across the border.

“The drug cartels in Juarez are just happier than all get-out because this gives them 500,000 free acres they will be able to drive through,” said Jack LeVick, executive director of the New Mexico Sheriffs’ Association.

New Mexico Sens. Tom Udall and Martin Heinrich, both Democrats, had proposed legislation to protect the region that includes popular hunting areas and features steep rock outcroppings, petroglyphs, ancient lava flows and sites such as Billy the Kid’s Outlaw Rock, Geromino’s Cave and the Butterfield Stagecoach Trail. Republican Rep. Steve Pearce, whose congressional district covers the region, meanwhile, had proposed the designation for just 55,000 acres.

The president will take the action using his authority under the Antiquities Act, administration officials said.

“I grew up hiking and exploring these public lands, and this new monument status preserves the outdoor heritage of the area and ensures continued access for hunting, grazing and outdoor recreation,” Michael Casaus, New Mexico director of The Wilderness Society, said in a statement.

Truman Project Executive Director and former U.S. Army Capt. Michael Breen said the designation will also protect important historic military sites.

“During World War II the Army Air Corps conducted trainings in and around the Organ Mountains,” he said in a statement. “They helped create secret navigational technology that shortened the war in Europe, saving lives. President Obama is making the right call by preserving these important military heritage sites.”

During a town hall meeting in Las Cruces earlier this year, however, some ranchers said they were concerned the designation would restrict what they can do on their land. Others said they were worried about its impact on water rights.

Earlier this year, Interior Secretary Sally Jewel hiked in the area and met with local officials. She also met with U.S. Border Patrol officials to underscore her agency’s commitment to cooperate when it comes to law enforcement along the border.

But LeVick said his group remains opposed to the plan and was drafting a letter to Obama.

Also Monday, Rep. Rob Bishop, R-Utah, wrote the president asking him to reconsider the decision in light of a recent violent attack on a National Park Service employee at Chiracahua National Monument in Arizona.